Drugs, foods, cosmetics, and other products to be kept in cleanliness have conventionally been filled and stored in sanitary containers in many instances. Such sanitary containers must be able to protect their contents from intrusion of microorganisms and also to prevent their contents from a quality change, deterioration or the like by ultraviolet rays or the like.
The intrusion of microorganisms into a container is prevented by sealing the container or hermetically closing the container with a rubber plug or the like, whereas the quality change, deterioration or the like of a content by ultraviolet rays or the like is avoided by adding a deterioration preventive to the content or incorporating an ultraviolet absorber in a sanitary container itself. Glass-made containers have conventionally been used for many years as containers most suited from the viewpoint of sanitation for drugs, nutrient solutions, transfusion solutions, foods and the like.
Soda-lime glass as a raw material for glass-made container is high in gas permeation resistance and water vapor permeation resistance (gas barrier properties) and has heat resistance, and also has relatively high chemical durability. Moreover it is of low price. Accordingly, glass-made containers are often made of soda-lime glass (soft glass). However, these glass-made containers involve glass-associated problems in that they are fragile and cannot store drug solutions having reactivity with silicon and drug solutions having high alkalinity. To avoid these glass-associated problems, there is now an increasing tendency to adopt plastic-made containers in place of glass-made containers.
Plastics have advantages over glass in that the former are lower in fragility, lighter in weight, and superior in moldability or formability compared with the latter. On the other hand, plastics are accompanied by disadvantages such that depending on the kinds of the plastics, they have low heat resistance and/or can provide molded or otherwise formed products with insufficient strength and/or with inferior gas transmission permeation and/or water vapor permeation resistance (gas barrier properties). Moreover, plastics also involve a serious problem to be solved in connection with ultraviolet ray transmission resistance (ultraviolet ray blocking property). Therefore, no plastics have heretofore been found yet to be equipped in a well-balanced manner with properties required for sanitary containers.
Concerning the light-shielding property (ultraviolet ray transmission resistance) of a colored container, the “Testing Method for Glass Containers for Injectable Preparations” in Item 7.01 of The Pharmacopoeia of Japan (fifteenth edition) specifies that the transmission rate should be 50% or lower at wavelengths of from 290 to 450 nm and 60% or higher (45% or higher in the case of a container that cannot be sealed by fusion and has a wall thickness of 1.0 mm or greater) at wavelengths of from 590 to 610 nm. In the United States, on the other hand, it is also specified in USP 31 General Chapter <671>, Table 2 that the transmission rate of a plastic bottle at wavelengths of from 290 to 450 nm differs depending on its capacity and should be, for example, 10% or lower for 50 mL capacity and 25% or lower for 1 mL capacity.
Under the foregoing situation, cyclic olefin polymers are known to be suited as plastics for sanitary containers. However, such cyclic olefin polymers are also high in ultraviolet transmission property like the conventional plastics, and sanitary containers made of these cyclic olefin polymers have a potential problem that their contents may be changed or deteriorated in quality by such rays. To avoid such a potential problem, there have been proposed inventions on sanitary containers, which make use of specific organic pigments as ultraviolet absorbers (Patent Documents 1 and 2).